Because it is

Because it is = juck food is an addictive drug?

Context:
Junk-fed rats have 'drug addict' brains
 18:00 28 March 2010 by Aria Pearson


Junk food may seem like an addictive drug because it is. In rats, at least, too much fatty food raises the threshold for feelings of satisfaction, sparking a cycle of compulsive overeating.

In people, addictive drugs such as heroin and cocaine desensitise the brain by raising the threshold of "reward" activity that is needed to feel satisfied: more drug is needed to achieve the same effect.